Documentation Index
Fetch the complete documentation index at: https://docs.sglang.io/llms.txt
Use this file to discover all available pages before exploring further.
1. Model Introduction
LTX-2 and LTX-2.3 are video generation models from Lightricks. SGLang Diffusion supports the LTX series through native one-stage and two-stage pipelines for text-to-video and image-conditioned video generation.
Use Lightricks/LTX-2 or Lightricks/LTX-2.3 as --model-path. For two-stage generation, SGLang uses the spatial upsampler and distilled LoRA components from the model snapshot by default. LTX-2.3 also supports the HQ two-stage variant.
License notice: LTX-2 and LTX-2.3 are released under the LTX-2 Community License Agreement, not Apache 2.0. The license includes commercial-use restrictions for some entities. Review the official Lightricks license before production or commercial use; SGLang support does not grant additional model usage rights. 2. SGLang-diffusion Installation
Install SGLang with diffusion dependencies:
uv pip install "sglang[diffusion]" --prerelease=allow
3. Model Deployment
This section provides deployment configurations optimized for different LTX pipelines and hardware targets.
3.1 Basic Configuration
The LTX series supports one-stage and two-stage pipelines. LTX-2.3 also supports the HQ two-stage pipeline. The recommended launch configuration depends on whether the target GPU can keep both two-stage DiTs resident.
Interactive Command Generator: Use the configuration selector below to generate a deployment command. The default selection targets a single NVIDIA H200 with resident two-stage mode. For multi-GPU serving, start from the 2-GPU or 4-GPU presets and only change parallelism if you need more memory headroom.
3.2 Configuration Tips
Choose the pipeline class based on the quality and latency target:
| Use case | Pipeline class | Notes |
|---|
| One-stage generation | LTX2Pipeline | Fastest LTX native path. Supports T2V and TI2V. |
| Two-stage generation | LTX2TwoStagePipeline | Uses a base stage and a refinement stage. Supported by LTX-2 and LTX-2.3. |
| Two-stage High Quality (HQ) generation | LTX2TwoStageHQPipeline | LTX-2.3 HQ path; defaults to 1920x1088 unless you override --width and --height. |
| Pipeline class | T2V | TI2V (--image-path) | LoRA (--lora-path) | Notes |
|---|
LTX2Pipeline | Yes | Yes | Yes | One-stage path. Cannot be combined with HQ because HQ is a separate two-stage pipeline class. |
LTX2TwoStagePipeline | Yes | Yes | Yes | Standard two-stage path for LTX-2 and LTX-2.3. |
LTX2TwoStageHQPipeline | Yes | Yes | Yes | High Quality two-stage path for LTX-2.3. Use this instead of LTX2Pipeline; it is not a one-stage mode flag. |
--ltx2-two-stage-device-mode controls transformer residency:
| Mode | When to use it |
|---|
snapshot | Recommended default. Balances latency and VRAM. |
resident | Best latency on high-VRAM GPUs because both DiTs can stay resident. |
original | Closest to the original two-stage switching semantics. |
--lora-path: Preload a community LoRA adapter.--lora-weight-name: Select the exact safetensors file when the LoRA repository contains multiple weight files.
For native LTX-2.3 two-stage serving without a user LoRA, resident is the fastest high-VRAM path. When you pass --lora-path, SGLang still applies the user LoRA during the two-stage switch, so use resident on H200-class GPUs for enough VRAM, but do not expect the same premerged-stage2 benefit as the no-user-LoRA path.
3.3 Fast multi-GPU presets
For latency-oriented LTX serving, prefer CFG parallel over sequence parallelism. CFG parallel splits guidance branches across GPUs, while SP/Ulysses is mainly a memory/long-sequence tool for LTX.
| Target | Recommended server flags | Notes |
|---|
| 1 high-VRAM GPU | --ltx2-two-stage-device-mode resident | Fastest two-stage setup when both DiTs fit. |
| 1 standard GPU | --ltx2-two-stage-device-mode snapshot | Lower VRAM than resident; use this when H100-class memory is tight. |
| 2 GPUs | --num-gpus 2 --enable-cfg-parallel --ltx2-two-stage-device-mode resident | Fastest common 2-GPU setup. |
| 4 GPUs | --num-gpus 4 --tp-size 2 --enable-cfg-parallel --ltx2-two-stage-device-mode resident | Fastest common 4-GPU layout: TP2 inside each CFG branch. |
| Official comparison | --ltx2-two-stage-device-mode original | Use this only when matching the original stage-switch semantics matters. |
--enable-cfg-parallel for degree-2 CFG parallel. Use --cfg-parallel-size only when you explicitly need a different CFG branch count. If resident exceeds available VRAM, keep the same parallelism preset and switch only the device mode to snapshot.
On high-VRAM GPUs, add --text-encoder-cpu-offload false if text encoding latency matters and you have enough memory.
3.3.1 Two GPUs
sglang serve \
--model-path Lightricks/LTX-2.3 \
--pipeline-class-name LTX2TwoStagePipeline \
--num-gpus 2 \
--enable-cfg-parallel \
--ltx2-two-stage-device-mode resident
3.3.2 Four GPUs
sglang serve \
--model-path Lightricks/LTX-2.3 \
--pipeline-class-name LTX2TwoStagePipeline \
--num-gpus 4 \
--tp-size 2 \
--enable-cfg-parallel \
--ltx2-two-stage-device-mode resident
4. Model Invocation
4.1 Basic Usage
The examples below spell out the current SGLang sampling defaults for reproducibility:
| Model path | Default output | Default frames | Default steps |
|---|
Lightricks/LTX-2 | 768x512 | 121 | 40 |
Lightricks/LTX-2.3 | 768x512 | 121 | 30 |
Lightricks/LTX-2.3 with LTX2TwoStageHQPipeline | 1920x1088 | 121 | 15 |
4.1.1 LTX-2 one-stage text-to-video
sglang generate \
--model-path Lightricks/LTX-2 \
--pipeline-class-name LTX2Pipeline \
--prompt "A quiet coastal town at sunrise, fishing boats moving slowly through golden mist, cinematic camera movement" \
--save-output
4.1.2 LTX-2.3 one-stage text-to-video
sglang generate \
--model-path Lightricks/LTX-2.3 \
--pipeline-class-name LTX2Pipeline \
--prompt "A quiet coastal town at sunrise, fishing boats moving slowly through golden mist, cinematic camera movement" \
--save-output
4.1.3 LTX-2 two-stage text-to-video
sglang generate \
--model-path Lightricks/LTX-2 \
--pipeline-class-name LTX2TwoStagePipeline \
--prompt "A handheld shot follows a red tram crossing a rainy city square at night, reflections on the pavement, cinematic lighting" \
--save-output
4.1.4 LTX-2.3 two-stage text-to-video
sglang generate \
--model-path Lightricks/LTX-2.3 \
--pipeline-class-name LTX2TwoStagePipeline \
--prompt "A handheld shot follows a red tram crossing a rainy city square at night, reflections on the pavement, cinematic lighting" \
--save-output
4.1.5 LTX-2.3 HQ text-to-video
sglang generate \
--model-path Lightricks/LTX-2.3 \
--pipeline-class-name LTX2TwoStageHQPipeline \
--prompt "A wide cinematic shot of alpine clouds rolling over a mountain ridge, soft morning light, slow aerial camera movement" \
--save-output
4.1.6 Image-to-video with one reference image
Pass one image to --image-path for image-conditioned generation:
sglang generate \
--model-path Lightricks/LTX-2.3 \
--pipeline-class-name LTX2TwoStagePipeline \
--image-path ./inputs/start.png \
--prompt "The camera slowly pushes forward as the subject turns toward warm window light, subtle natural motion, cinematic" \
--save-output
4.1.7 First-to-last-frame transition with two reference images
Pass two images to --image-path for transition-style TI2V. The first image is used as the starting condition and the second image is used as the ending condition.
sglang generate \
--model-path Lightricks/LTX-2.3 \
--pipeline-class-name LTX2TwoStagePipeline \
--image-path ./inputs/start.png ./inputs/end.png \
--prompt "A smooth cinematic transition from the first scene into the final scene, dynamic camera motion, motion blur, zhuanchang" \
--save-output
4.2 Advanced Usage
Use --lora-path to load a LoRA adapter. If the Hugging Face repo contains multiple safetensors files, use --lora-weight-name to select the exact file. --lora-scale maps to the standard LoRA merge scale and defaults to 1.0.
The following example uses valiantcat/LTX-2.3-Transition-LORA:
sglang generate \
--model-path Lightricks/LTX-2.3 \
--pipeline-class-name LTX2TwoStagePipeline \
--lora-path valiantcat/LTX-2.3-Transition-LORA \
--lora-weight-name ltx2.3-transition.safetensors \
--prompt "A low-angle tracking shot moves through a foggy forest road. The camera rises above the treetops and transitions into a clear view of a snowy mountain peak under bright sunlight, zhuanchang" \
--save-output
sglang generate \
--model-path Lightricks/LTX-2.3 \
--pipeline-class-name LTX2TwoStagePipeline \
--image-path ./inputs/start.png ./inputs/end.png \
--lora-path valiantcat/LTX-2.3-Transition-LORA \
--lora-weight-name ltx2.3-transition.safetensors \
--prompt "A fast cinematic transition from the first image to the second image, whip-pan motion, atmospheric lighting, zhuanchang" \
--save-output
Some community LoRAs only include weights for transformer blocks. In that case, SGLang logs a concise coverage summary and leaves unmatched LoRA-capable layers on the base model weights. This is expected when the adapter format intentionally omits those layers.
5. Practical Tips
- Use
--pipeline-class-name LTX2TwoStagePipeline as the default LTX two-stage quality path.
- Use
--pipeline-class-name LTX2TwoStageHQPipeline when you want the HQ path and have enough VRAM for larger outputs.
- Use
--ltx2-two-stage-device-mode resident on high-VRAM GPUs if latency matters more than memory usage.
- Use
--ltx2-two-stage-device-mode original when comparing against official two-stage behavior.
- Keep
--width and --height aligned with the target model resolution; for LTX models, these are output video dimensions.
